The relationship between paediatric foot posture and body mass – do heavier kids really have flatter feet?

Abstract

Background The prevailing opinion is that heavier children have flat-ter feet, a consistent finding of the studies that have addressed this issue. Recently, we queried this observa-tion and postulated that the method of foot posture assessment may influence this finding, as there was no positive relationship between the BMI and FPI-6 scores of 140 school children. Most other studies have used footprint-based measures. Methods Data was acquired from four datasets from previous works, (South Australia, n=303; UK, n=225; rural South Australia, n=140; New Zealand, n=30) providing 698 observations of children's BMI and FPI-6 scores. Descriptive statistics were used to examine the basic anthropometrical characteristics of the study popula-tions. Parametric statistical correlations were applied to continuous data, and scatter plots were used to explore and illustrate relationships between parameters. Results The total population results yielded the following mean (SD): age 9.20 years (2.34), BMI 18.29 kg/m 2 (3.52), FPI-6 4.68 – 4.95 (3.12 – 3.31). Gender N = 698; 359M: 339F. Correlations between BMI and FPI-6 ranged from – 0.89 (p=0.05) to -0.115 (p=0.01) for the study population (n = 698) aged from 3 to 15 years. The mean population (n=698) BMI = 18.29 kg/m 2 (3.51), whereas the mean BMI for the 'flatfoot' (FPI-6 ≥ 6, n=267) = 18.16 kg/m 2 (3.73) and the 'non flat-foot' group BMI (FPI-6 < 6, n=431) = 18.51 (3.43). Using the international obesity task force cut-off points for overweight, the study population was also evaluated for BMI/foot posture (FPI-6) for each age year group. Conclusion This study supports our earlier findings, and conflicts with many other studies, in not finding a positive corre-lation between increased BMI and 'flatter' feet in chil-dren. Clinically, these findings question the need for concern about children's BMI as a specific influence on (flatter) foot posture, and also the validity of footprint based measures.